Let’s work an example. Lets say you measure the mobile antenna discussed in the last article in this series, and you measured VSWR=4.61 and |Z|=209Ω, we can calculate R and |Z| using the calculator above.

The results tell us that R is 191Ω, |X| is 84.1Ω, and the magnitude of phase angle of Z |θ| is 23.7°, we are fairly close to a voltage maximum.

Don’t try to work the answers out for the Mini60 demo display at the top of this article, the displayed values are inconsistent, ie physically impossible. If VSWR(50)=1.35, |Z| cannot be less than 50/1.35=37Ω. Alternatively, if R=33Ω and |Z|=34Ω, then |X|=8.2Ω and VSWR=1.58. The values shown on the display are consistent with Zo=40Ω. (Why would you publish a promotional video that questions the quality of the instrument?)

Summary

It is possible to calculate R and |X| from VSWR and |Z|, but tedious.

Check the consistency of instrument results before you put faith in them.